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A Case Study in Ecological Succession

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A Case Study in Ecological Succession A case study in ecological succession Ecological succession is a fundamental principle in ecology. It is the change in species and habitat structure that an Geospatial referencing before modern technology ecosystem undergoes over time. Plant succession depends on management. For example, with no management—fire, Changes at the Fitch Reservation mowing or grazing—on the Reservation since 1948, the formerly open grasslands and fields have given way to woodland. Henry Fitch recorded location data for tens Plant communities, in turn, affect animal distribution. The landscape Henry and Virginia Fitch encountered when they came to live here in 1948 is of thousands of records of capture-release gone. Henry Fitch noted great changes in land cover and animal species as they took place. In points for animals, plant transects and a During his tenure here, Henry Fitch documented changes in plants and animals as succession proceeded, setting the stage for a 1998 interview for the journal Copeia, he said, “Every animal species has changed in myriad of other data. distribution and abundance, and in general, the grassland species, especially those of shortgrass, future research. When the Reservation was established in the 1940s, the idea of protecting an area from disturbance—“hands have disappeared,” and also, “Every part of the Reservation’s square mile has changed, to the He accomplished this—before the availability off; let nature take its course”—was the prevailing wisdom. Now we understand that management that mimics natural extent that it is hardly recognizable as the same area I first saw … .” Bob Gress of georeferencing equipment—by using a processes (fire and native grazers) under which communities evolved is vital to native ecosystems. Because of Fitch’s thorough This image cannot currently be displayed. two-tiered system: 1) record the general research methods, this area is now a well-documented natural experimental site considering ecological succession and land Ecological drivers: Agents of change location according to the name of a field (or An ecological driver is something that causes change in the landscape. For use history effects on ecosystems. Fitch’s long-term data now support a range of scientists, from single investigators to example, fire is an abiotic (nonliving) driver because it kills trees and shrubs. An subdivision); and 2) within the field, record invasive plant, such as bush honeysuckle, is a biotic driver because it can multidisciplinary teams. outcompete native plants and thus decrease biological diversity of a forest. distance and direction from a landmark, such Deer are ecological drivers in forests. As browsers, they feed on trees, as a tree, a fence corner, a large rock or a shrubs and vines. They may feed selectively, causing drastic reductions in certain cultural feature. Fitch might have described tree species. When deer populations in this area are high you will see a distinctive browse line, which means that less of the available woody the place where you are standing now as vegetation is found below the level the deer can reach. Deer also feed selectively on some herbaceous plants, and their impacts on spring-blooming “House Field, 60 feet east-northeast of Road forest wildflowers can be devastating. Locust [tree].” Historically deer had native predators in this region (such as wolves and White-tailed deer (Odocoileus virginianus) were eliminated from this area by mountain lions) that controlled their populations; now regulated management overhunting in the 1800s. They were first sited again in 1949 and repopulated by hunting is often used to keep the population in check and protect other the area as woody vegetation became more abundant and provided food and Fitch named and used more than 700 (Above) Boundary types Fitch ecosystem components. shelter. Now deer or their “sign” are seen commonly. landmarks. With his help, KU scientists have used to demarcate locations; there are 80 subdivisions. (Right) “Tomb Photos: Bob Gress georeferenced and computerized his Rock” in “Dam Woods” as seen Other examples of change with Chester Fitch for scale in landmarks and boundaries so that a record November 1958. This landmark Changes in abundance: Habitat shifts remains, whereas many large Two pit vipers occur on the Reservation, the Timber Rattlesnake (Crotalus is maintained, making his data extremely landmark elms died from Dutch horridus, left) and the Copperhead (Agkistrodon contortrix, right). These animals Elm disease; their presence is now have heat-detecting structures in their heads that allow them to detect and valuable to science. known only from maps. strike at prey, injecting a paralyzing or lethal dose of venom. Both snakes were fairly common here in the late 1940s and the 1950s, but their numbers declined greatly as grasslands disappeared (through ecological succession). Habitat (Right) The same two images as those in the center of this panel are changes meant a decline in the small rodents they depended on for food. superimposed with the boundaries of “farm fields, pastures, meadows, and woodlands” that Fitch identified when he arrived in 1948. These are Changes in abundance: Unknown causes historic management units. Because land use history leaves an indelible Skunks are omnivores, feeding on a wide diet of plant and animal origin. In 1948, imprint on the landscape and changes the trajectory of ecological the spotted skunk (Spilogale putorius, left) was common here. The spotted skunk succession, access to this information is critical to interpreting current declined and has not been seen here for decades, nor in much of eastern conditions. For example, a plowed field would have a different Kansas, but the striped skunk (Mephitis mephitis, right) is common. Biologists are composition of trees after a few decades than a former grassland pasture not sure why this has occurred. would have. (Distance to seed source of colonizing trees and other factors also are important.) Changes in occurrence: New sightings The Reservation has been studied by scientists and visited by naturalists for As woody succession resulted in declines in snake numbers on the decades, yet occasionally a species not known to occur here is reported. In 2014, Reservation, Fitch expanded his sampling to areas of the KU Field Station two vertebrate species were first seen. The Lazuli Bunting (Passerina amoena, left) adjacent to the Reservation where prairie, grasslands and other habitats 1941 2012 1941 is normally common much farther west, yet several individuals were spotted here flourished. Unlike the Reservation, these areas were maintained by 2012 that spring. The Nine-banded Armadillo (Dasypus novemcinctus, right) has expanded burning, mowing and grazing. Fitch wrote in his 1999 book on his its range northward from Texas and Mexico coincident with milder winters. decades-long study of snakes at the Reservation that by the mid-1980s Although armadillos have been observed in Kansas for several years, summer other parts of the Field Station, which were actively managed, were 6 2 These aerial views show woodland development on the Fitch Reservation (recall that there has been no management here since 1948). In 1941, the area was treated as a farm with plowed fields, open pastures, tallgrass prairie and forested 2014 was the first time an armadillo was seen on the Reservation. producing vegetation that resembled the early successional stages of slopes. Currently, viewed from above, the area has the aspect of a closed canopy forest. those on the Reservation 35 years earlier. U.S. Forest U.S. Forest Service 1 National Ecological Observatory Network (NEON) (Right) Color infrared (CIR) imagery is a technique used to 1 Fitch recording data on a This July 1997 sample, Fitch measuring a analyze vegetation types across the landscape. Different plants give off 3 Prairie Kingsnake at the KU one of Fitch’s thousands Black Rat Snake in Fitch’s long-term data contributes to the importance of the Reservation as a site in the different “signatures” that indicate the type of plant community You are here 5 Field Station’s Nelson of field data sheets, coded an area where red National Science Foundation’s groundbreaking NEON project. The continent-wide present. Signature intensity and character change seasonally and with Environmental Study Area biological data on cedars have project is aimed at understanding the impact of climate change, land use change and land management. This aerial image from 2002 shows complexity in the (NESA), adjacent to the Agkistrodon contortrix succeeded former invasive species on the nation’s natural resources. KU Field Station sites were selected Fitch Reservation and adjoining KU Field Station lands. Legacy imprints 4 Reservation. In Fitch’s field (Copperhead) and his agricultural fields. to represent areas where tallgrass prairie once dominated, but where prairie had given include areas of red cedars vs. deciduous forest, as well as the 2 data, this is referred to as two-tiered location way and woodlands increased. + persistence of some grassland and other specific features. * 4 EMP (Electric Mouse Pens), system: i.e., general his name for the large metal location (“EMP”) and Fitch’s intense desire to understand ecological relationships sometimes put him ahead KEY enclosure, seen in the specific location (e.g., of his time. His view of the Reservation’s mission, as articulated in a 1952 paper, seems (1) Cool-season grasses (mostly introduced species, e.g., brome) background, used for small “100’ W of SE corner”). to foresee NEON: “This is intended to be a permanent research station, with a long- have a pinkish signature. 1, 2 1 term program of study … . Continued collaborative effort by various specialists *Approximate locations mammal research. The area of the Fitch Reservation (2) Warm-season grasses (mostly native species, e.g., big had an electric fence on top working together will ultimately provide unusual insight into these interrelationships.” (*) and Konza Prairie (+) bluestem) have a bluish hue. to discourage disturbance by (3) Eastern red cedar trees have a deep reddish-brown signature.
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